A light-sensitive material having a light-sensitive layer containing silver halide, a reducing agent and a polymerizable compound provided on a support can be used in an image forming method in which a latent image of silver halide is formed, and then the polymerizable compound is polymerized to form the corresponding image.
Examples of said image forming methods are described in Japanese Patent Publication Nos. 45(1970)-11149 (corresponding to U.S. Pat. No. 3,697,275), 47(1972)-20741 (corresponding to U.S. Pat. No. 3,687,667) and 49(1974)-10697, and Japanese Patent Provisional Publications Nos. 57(1982)-138632, 57(1982)-142638, 57(1982)-176033, 57(1982)-211146 (corresponding to U.S. Pat. No. 4,557,997), 58(1983)-107529 (corresponding to U.S. Pat. No. 4,560,637), 58(1983)-121031 (corresponding to U.S. Pat. No. 4,547,450) and 58(1983)-169143. In these image forming methods, when the exposed silver halide is developed using a developing solution, the polymerizable compound is induced to polymerize in the presence of a reducing agent (which is oxidized) to form a polymer image. Thus, these methods need a wet development process employing a developing solution. Therefore, the process takes a relatively long time.
An improved image forming method employing a dry process is described in Japanese Patent Provisional Publications Nos. 61(1986)-69062 and 61(1986)-73145 (the contents of both publications are described in U.S. Pat. No. 4,629,676. In this image forming method, a recording material (i.e., light-sensitive material) comprising a support and a light-sensitive layer provided thereon which contains a light-sensitive silver salt (i.e., silver halide), a reducing agent, a cross-linkable compound (i.e., polymerizable compound) and a binder is imagewise exposed to form a latent image, and then the material is heated to polymerize within the area where the latent image of the silver halide has been formed. The above method utilizing the dry process and the light-sensitive material employable for such method are also described in Japanese Patent Provisional Publications Nos. 61(1986)-183640, 61(1986)-188535 and 61(1986)-228441.
The above-mentioned image forming methods are based on the principle in which the polymerizable compound is polymerized in the portion where a latent image of the silver halide has been formed.
Further, Japanese Patent Provisional Publication No. 61(1986)-260241 describes another image forming method in which the polymerizable compound in a portion where a latent image of the silver halide has not been formed is polymerized. In the method, when the material is heated, the reducing agent functions as polymerization inhibitor in the portion where a latent image of the silver halide has been formed, and the polymerizable compound in other portion is polymerized.
Japanese Patent Provisional Publications Nos. 61(1986)-275742 and 61(1986)-278849 describe an embodiment of the light-sensitive material, which employs microcapsules containing at least two components composing the light-sensitive layer, that is, a polymerizable compound and a color image forming substance. The light-sensitive material having such structure has an advantage of giving an image of high quality. The silver halide is generally contained in the microcapsules for the purpose of image formation in high sensitivity.
In the above-mentioned light-sensitive material employing the microcapsules, a shell of the microcapsule preferably has high strength (firmness) and high denseness from the viewpoints of enhancement of preservability of the light-sensitive material and easiness in handling thereof. The above publications also describe preferred examples of the shell materials for the microcapsules such as a polyurea resin and a polyurethane resin, or a urea/formaldehyde resin. Further, a variety of shell materials for the microcapsules are also proposed in various publications such as Japanese Patent Provisional Publications Nos. 62(1987)-209437, 62(1987)-209438, 62(1987)-209439, 62(1987)-209440, 62(1987)-209441, 62(1987)-209447 and 62(1987)-209442. Particularly, an amino-aldehyde resin described in the Japanese Patent Provisional Publication No. 62(1987)-209439 is very excellent in firmness and denseness.
In the light-sensitive materials having the above-mentioned constitution, a variety of other substances for accelerating image information such as base and base precursor (referred to as "image formation accelerator") are generally contained in the light-sensitive layer (not in the microcapsules). However, the present inventors have found that the effect given by incorporation of the image formation accelerator is not sufficiently shown when an image is formed using the above light-sensitive material containing the microcapsules of high denseness.